Mike Sigman, prior owner of Dave's plane wrote:

> The pitot was set at 3 7/8". on straight and level the 

> airspeed appeared to be within 5 kts accurate but in a 

> high incident stall climb the indicated speed appeared 

> to be high.

 

Hmmm, I'd expect that the ASI should be within 1 mph at 100 mph, per some
published spec.  Mine was (once I'd replace the bad ASI with a new one).

 

Five knots is a lot of error at cruise speed, but is typical for a failing
ASI.  Mine was claiming 10-15 mph higher than my true airspeed.

 

Why was I having headwinds both directions on every flight, compared to my
flight plan, I wondered.  Back then, I had to use a much more difficult
flight test to check it but the results were conclusive.  The careful flight
test after replacing the ASI was also conclusive that my new ASI was spot on
at 100 mph.

 

The simple flight test linked from the ASI article is easy to fly and the
website does all the computation.  If t'were me, I'd go find out.

http://edburkhead.com/Ercoupe/airspeed_indicator_errors.htm (see the link at
the bottom)

http://www.reacomp.com/true_airspeed/index.html 

 

Ed

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